You can either use the tag a single way Way drawn along the whole route, or on a relation Relation (type=route) containing several ways joined end-to-end. More infomations=traffic lines.

traffic lines

A type=route is a customary or regular line of passage or travel, often predetermined and publicized. Routes consist of paths taken repeatedly by people and vehicles: a ship on the North Atlantic route, a car on a numbered road, a bus on its route or a cyclist on a national route.
A route (or variant) may belong to a route type=route_master. A route master contains all the directions, variant routes and information for that route. It permits OSM to distinguish the two routes of a two-way trip.

Members

Station

evidence: Use the disused: lifecycle prefix on tags that relate to features that are in a reasonable state of repair but which are currently disused:abandoned: .(example: disused:railway=station).

railway

station

Railway stations (including main line, light rail, subway, etc.) are places where customers can access railway services. railway=station should be applied to a node placed at the center of the station area, from the passengers' point of view (i.e. near platforms).

halt

Stations without switches where only passenger trains stops are called halts, not stations. They are tagged railway=halt A small station, may not have a platform, trains may only stop on request.

tram_stop

A tram stop is a place where a passenger can embark/disembark a tram. It generally comprises a sign, maybe with a small shelter, timetable and facilities for unattended ticket sales (vending machines). There are no operating staff present.

subway

yes

subway-Station

public_transport

station

The public_transport=station is used to tag properties associated with a railway station/port/airport/bus station/coach interchange etc.Public-Transport-Schema. Dont use the tag at goods traffic.

halt point (vehicle)

Use public_transport=stop_position to identify the place where a vehicle stops along a public transport route to pick up or drop-off passengers (put the point in the middle of the track from the platform). This tag can be used for any transport mode, or combination of transport modes (including rail, bus, tram, flight, taxi and ship).
Use {tag|public_transport|platform}} and/or {tag|highway|bus_stop}} to identify the places where passengers wait for the service.